Agrometeorological Assessment of Thermal Indices, Phenology and Canopy Temperature Dynamics in Green Gram under Different Sowing Windows and Varieties

Background: Green gram (Vigna radiata L.), locally called moong, is a high-protein pulse crop that improves soil fertility through nitrogen fixation and serves as food, cattle feed, and green manure. Its growth and yield are strongly influenced by weather, sowing time, and variety, with optimal planting enhancing productivity and resource-use efficiency. Aim: To assess the impact of the thermal indices, phenological development, and canopy temperature depression (CTD) under different sowing windows and varieties to optimize sowing strategies for enhanced crop resilience and yield stability in green gram. Study Design: Factorial Randomized Block Design (FRBD). Place and Duration of Study: AICRP on Agrometeorology farm, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, during the 2023-24 kharif season. Methodology: Nine treatments including three sowing windows, viz., D1- 28th MW (10th July), D2- 29th MW (17th July) and D3- 30th MW (24th July) as main plots, and three varieties, viz., V1- PKV Green Gold, V2- PKV AKM-4 and V3- Utkarsha as sub-plots replicated thrice. Results: Crops sown in the 28th MW (1108 °C day) window accumulated the highest GDD, which decreased by 7.5% in 29th MW, and 10.5% in 30th MW. Similarly, the highest PTU were observed in 28th MW (14993 °C day hrs), followed by 29th and 30th MW with a decrease of 7.5% and 10.7%, respectively. These trend was continued for TUE with the maximum achieved under 28th MW (2.5 kg ha-1°C-1 day-1), succeeded by 29th and 30th MW with a decline of 8.4% and 16.0%, respectively. On the other hand, late sowing (30th MW) achieved the highest HTU (3932 °C day hrs), followed by 28th and 29th MW with a reduction of 4.3% and 9.4%, respectively. Maximum CTD was found in 28th MW (1.23 °C), which reduced with delayed sowing in 29th (40.7%) and 30th MW (42.3%). Among the varieties, PKV Green Gold exhibited the highest GDD, PTU, HTU, and CTD, ensued by PKV AKM-4 while Utkarsha recorded the lowest. Soil moisture content was the highest in 28th MW sowing, except at the pod initiation stage. Correlation analysis revealed that the optimal crop development was influenced by certain weather conditions, such as cooler temperatures that favoured emergence and maturity, while higher minimum temperatures supported flowering. Conclusion: Sowing in 28th MW optimized thermal indices and yield efficiency, while delayed sowing (29th and 30th MW) showed reduction, as late sowing lead to the forced maturity of crop. PKV Green Gold exhibited the highest GDD, PTU, and CTD, whereas PKV AKM-4 demonstrated the better efficiency to utilize available thermal units. This study will prove an important step towards deciding appropriate sowing time for maximizing growth and yield of crop under varying weather conditions.